Orange County Chapter occnps.org California Native Plant Society HAVE YOU SEEN THIS PLANT? It is an Emergent Invasive in Orange County

YELLOW STAR THISTLE Centaurea solstitialis

Known OC sites & Status Updates

Distribution map & info: • calflora.org/cgi-bin/species_query.cgi? where-calrecnum=1853 Flowering & seed production occur from April to September • cal-ipc.org/ip/management/plant_profiles/ Centaurea_solstitialis.php

Can be confused with: Tocalote, Centaurea melitensis

Yellow star thistle is a highly invasive, bushy winter annual, up to 3 + ft. It inhabits open hills, grasslands, open woodlands, fields, roadsides, & rangelands. It is toxic to livestock & is considered one of the most serious rangeland weeds in the state.

It propagates rapidly by seed. A large plant can produce nearly 75,000 seeds, which are wind-dispersed. Orange County Chapter occnps.org California Native Plant Society YELLOW STAR THISTLE, P. 2

IF YOU SEE THIS PLANT AT A SITE THAT’S NOT ON THE LIST: • Record the plant’s location as exactly as you can (GPS coordinates if possible), the date you saw it, and an estimate of how many there were. Include the site’s landowner or manager, if known. • Take identifying photos: the whole Centaurea solstitialis: Centaurea melitensis: note the long straight note the shorter, plant & its surroundings, closeups of stout spines curved spines leaves & flowers. • If you take a sample, place it immediately into a sealed bag. • To avoid spreading the plant, check your clothing and shoes thoroughly before leaving the area, and remove and bag all traces of seeds. • Report the find immediately to [email protected].